Heavy metal contamination in water poses a critical threat to human and environmental health, particularly in regions where mining and industrial activities occur or where agrochemicals are used intensively. In this context, natural bioadsorbents emerge as sustainable, cost-effective, and environmentally friendly alternatives to conventional treatment technologies. This chapter provides a comprehensive review of the current research on using lignocellulosic materials, agricultural waste, and functionalized biomaterials to remove heavy metals, including lead, cadmium, mercury, zinc, and chromium. The analysis covers adsorption mechanisms, surface modification methodologies, efficiency under real conditions, and technological scaling challenges. Technical, economic, and regulatory limitations that have prevented their widespread adoption are also discussed. The analysis is framed within the context of the Sustainable Development Goals (SDGs), particularly SDGs 6 (clean water and sanitation), 3 (health and well-being), 12 (responsible production and consumption), and 13 (climate action). The review concludes with a discussion of priority areas for future research and proposes synergies between technological innovation, the circular economy, and public policy to enhance the impact of bioadsorbents on global environmental sustainability.